Intranasal mite allergen induces allergic asthma-like responses in NC/Nga mice

Exosomes Derived from Dermatophagoides farinae Induce Allergic Airway Inflammation

House dust mites (HDMs) are a major source of indoor allergens that cause airway allergic disease. Dermatophagoides farinae, a predominant species of HDMs in China, has demonstrated pathogenic role in allergic disorders. Exosomes derived from human bronchoalveolar lavage fluid have been strongly associated with allergic respiratory diseases progression. However, the pathogenic role of D. farinae-derived exosomes in allergic airway inflammation has remained unclear until now. Here, D. farinae was stirred overnight in phosphate-buffered saline, and the supernatant was used to extract exosomes by ultracentrifugation. Then, shotgun liquid chromatography-tandem mass spectrometry and small RNA sequencing were performed to identify proteins and microRNAs contained in D. farinae exosomes. Immunoblotting, Western blotting, and enzyme-linked immunosorbent assay demonstrated the specific immunoreactivity of D. farinae-specific serum IgE antibody against D. farinae exosomes, and D. farinae exosomes were found to induce allergic airway inflammation in a mouse model. In addition, D. farinae exosomes invaded 16-HBE bronchial epithelial cells and NR8383 alveolar macrophages to release the inflammation-related cytokines interleukin-33 (IL-33), thymic stromal lymphopoietin, tumor necrosis factor alpha, and IL-6, and comparative transcriptomic analysis of 16-HBE and NR8383 cells revealed that immune pathways and immune cytokines/chemokines were involved in the sensitization of D. farinae exosomes. Taken together, our data demonstrate that D. farinae exosomes are immunogenic and may induce allergic airway inflammation via bronchial epithelial cells and alveolar macrophages. IMPORTANCE Dermatophagoides farinae, a predominant species of house dust mites in China, has displayed pathogenic role in allergic disorders, and exosomes derived from human bronchoalveolar lavage fluid have been strongly associated with allergic respiratory diseases progression. However, the pathogenic role of D. farinae-derived exosomes in allergic airway inflammation has remained unclear until now. This study, for the first time, extracted exosomes from D. farinae, and sequenced their protein cargo and microRNAs using shotgun liquid chromatography-tandem mass spectrometry and small RNA sequencing. D. farinae-derived exosomes trigger allergen-specific immune responses and present satisfactory immunogenicity, as revealed by immunoblotting, Western blotting, and enzyme-linked immunosorbent assay and may induce allergic airway inflammation via bronchial epithelial cells and alveolar macrophages. Our data provide insights into the mechanisms of allergic airway inflammation caused with D. farinae-derived exosomes and the treatment of house dust mite-induced allergic airway inflammation.

Strain-Specific Differences in House Dust Mite (Dermatophagoides farinae)-Induced Mouse Models of Allergic Rhinitis

Objectives.

Limited information is available regarding strain-related differences in mouse models of allergic rhinitis induced by Dermatophagoides farinae (Der f1). In this study, we compared differences between two mouse strains and determined the optimal dose of Der f1 for allergic rhinitis mouse models.

Methods.

Forty-eight mice were assigned to the following six groups (n=8 per group): group A (control, BALB/c), group B (Der f1-sensitized BALB/c, 25 µg), group C (Der f1-sensitized BALB/c, 100 µg), group D (control, C57BL/6), group E (Der f1-sensitized C57BL/6, 25 µg), and group F (Der f1-sensitized C57BL/6, 100 µg). Allergic inflammation was induced with Der f1 and alum sensitization, followed by an intranasal challenge with Der f1. Rubbing and sneezing scores, eosinophil and neutrophil infiltration, and immunoglobulin, cytokine, and chemokine levels in the nasal mucosa and from splenocyte cultures were assessed.

Results.

Rubbing and sneezing scores were higher in groups B, C, E, and F than in groups A and D, with a similar pattern in both strains (i.e., group B vs. E and group C vs. F). Serum immunoglobulin levels were significantly elevated compared to the control in groups B and C, but not in groups E and F. Eosinophil and neutrophil infiltration increased (all P<0.05) after the Der f1 challenge (groups B, C, E, and F) compared to the control (groups A and D) in both the BALB/c and C57BL/6 strains, without any significant difference between the two strains (group A vs. D, group B vs. E, and group C vs. F) (P>0.05). BALB/c mice (group B) showed a greater elevation of splenic interleukin (IL)-4 (P<0.01), IL-5 (P<0.01), and IL-6 levels (P<0.05) and nasal IL-4 mRNA levels (P<0.001) than the C57BL/6 mice (group E). Interestingly, mice treated with 100 µg Der f1 showed a weaker allergic response than those treated with 25 µg.

Conclusion.

We found 25 µg to be a more appropriate dose for Der f1 sensitization. BALB/c mice are more biased toward a Th2 response and are a more suitable model for allergic rhinitis than C57BL/6 mice. This study provides information on the appropriate choice of a mouse model for allergic rhinitis.

Human albumin augmented airway inflammation induced by PM2.5 in NC/Nga mice

The synergic allergic inflammatory effects of particulate matter (PM) 2.5 and human albumin were investigated in NC/Nga mice, which are hypersensitive to mite allergens. PM2.5 or PM2.5 plus human albumin with aluminum oxide was injected twice intraperitoneally for sensitization. After 7 days, PM2.5 or PM2.5 plus human albumin was administered five times intranasally to mice for further sensitization. Subsequently, PM2.5 was administered as a challenge on the 11th day. On the 12th day, mice were examined for airway hyperresponsiveness (AHR), bronchoalveolar lavage fluid (BALF) cell count, mRNA expression of Th₁ , Th₂ cytokines, chemokines, and mucus proteins (MUC5AC and MUC5B) in the lung tissue and histopathology. Although PM2.5 or human albumin alone did not induce allergic airway inflammation, simultaneous inoculation of PM2.5 and human albumin-induced airway inflammation showing increase in AHR, total BALF cell numbers, mRNA levels of IL-13, eotaxin 1, eotaxin 2, and MUC5AC, and anti-IG against human serum albumin. Inflammation was observed around the bronchus in PM2.5 plus human albumin-induced lungs. These results demonstrate that PM2.5 can induce allergic airway inflammation through the synergistic action with human albumin in NC/Nga mice.

Mouse NC/Jic strain provides novel insights into host genetic factors for malaria research

Malaria is caused by Plasmodium parasites and is one of the most life-threatening infectious diseases in humans. Infection can result in severe complications such as cerebral malaria, acute lung injury/acute respiratory distress syndrome, and acute renal injury. These complications are mainly caused by P. falciparum infection and are major causes of death associated with malaria. There are a few species of rodent-infective malaria parasites, and mice infected with such parasites are now widely used for screening candidate drugs and vaccines and for studying host immune responses and pathogenesis associated with disease-related complications. We found that mice of the NC/Jic strain infected with rodent malarial parasites exhibit distinctive disease-related complications such as cerebral malaria and nephrotic syndrome, in addition to a rapid increase in parasitemia. Here, we focus on the analysis of host genetic factors that affect malarial pathogenesis and describe the characteristic features, utility, and future prospects for exploitation of the NC/Jic strain as a novel mouse model for malaria research.

Involvement of PM2.5-bound protein and metals in PM2.5-induced allergic airway inflammation in mice

BACKGROUND

The aim of this study was to investigate the protein and trace element components of PM2.5 and their contribution to the allergic airway inflammation in BALB/c mice.

METHODS

PM2.5, treated at high temperature and with a strong acid to hydrolyze any protein content and remove trace elements, was administered to BALB/c mice. Allergic airway inflammation was compared between the three groups (saline, pure PM2.5 and treated PM2.5) by evaluating airway hyperresponsiveness (AHR), bronchoalveolar lavage fluid (BALF) cells, serum IgE, the mRNA of various cytokine (IL-4, IL-5, IL-13, eotaxin-1 and CXCL3), mucus protein mRNA (MUC5ac and MUC5b) and the filtration of inflammatory cells in the lung.

RESULTS

The treatment of PM2.5 with a strong acid at a high temperature attenuated AHR, eosinophil percentage in BALF, mRNA levels of IL-13 and CXCL3 and peribronchial inflammation. On the contrary, the percentage of neutrophils in BALF, mRNA expression of MIP2α, EGFR, Nrf2, and TLR4 and 4-OH-2-nonenal levels in the lung was increased. Moreover, the treatment of the PM2.5 reduced PM2.5-bound proteins as well as the percentages of the trace elements in PM2.5 in the order Zn > Cu >  Pb > P > S > Mn > Fe > Ca > Ni, whereas the percentage of C, Si and Cl increased.

CONCLUSIONS

PM2.5 collected by of the cyclone system induced allergic airway inflammation in mice. PM2.5-bound proteins and acid-soluble metals may be involved in the pathogenesis of PM2.5-induced allergic airway inflammation.

Bleomycin Aggravates Atopic Dermatitis via Lung Inflammation in 2,4-Dinitrochlorobenzene-Induced NC/Nga Mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Bleomycin (BLM) contributes to the induction of pulmonary inflammation and fibrosis in animals. Although skin and lung tissue inflammation is closely related in the pathogenesis of allergic diseases, a proper animal model for investigating the relationship between skin and lung inflammation is lacking. Therefore, we developed a mouse model of AD with relapsing dermatitis and pulmonary fibrosis caused by the administration of allergen and BLM. The present study determined whether lung injury caused by the bronchial application of BLM would exacerbate AD-like allergic inflammation induced by 2, 4-dinitrochlorobenzene (DNCB) in NC/Nga mice. NC/Nga mice treated with BLM and DNCB had increased severity of clinical symptoms and airway hyperresponsiveness as well as increased inflammatory cell infiltration and collagen deposition in the dorsal skin and lung. Compared to normal mice, interleukin (IL)-6 and tumor necrosis factor (TNF)-α production in bronchoalveolar lavage fluid were increased in NC/Nga mice treated with both DNCB and BLM and in animals treated with DNCB alone. Administration of BLM and DNCB increased the levels of IL-4 and IL-13 production in spleen cells and eotaxin-2 mRNA expression in dorsal skin, compared to NC/Nga mice treated with DNCB alone. The total cell numbers in axillary lymph node, bronchoalveolar lavage, and thymus were increased in DNCB-BLM mice compared to those in mice treated with DNCB alone. Administration of BLM and DNCB increased the numbers of cluster of differentiation 4 (CD4)+ T cells and CD11b+granulocyte-differentiation antigen-1 (Gr-1)+ cells among peripheral blood mononuclear cells, CD4+ cells in bronchoalveolar lavage, CD4+ and B220+CD23+ B cells in the axillary lymph node, and CD4+ cells in thymus, compared to DNCB-treated mice. The number of total, CD4+, and CD11b+Gr-1+ cells in the lung were increased in both DNCB and DNCB-BLM mice. These results demonstrate that BLM aggravates allergic skin inflammation and promotes airway hyperreactivity and lung inflammation when combined with DNCB in NC/Nga mice.

Human lactoferrin induces asthmatic symptoms in NC/Nga mice

Lactoferrin in commercial supplements is known to exert anti‐viral and anti‐allergic effects. However, this is the first study to evaluate the induction of allergic airway inflammation in NC/Nga mice. Human lactoferrin was administered intraperitoneally with aluminum oxide for sensitization. Five days later, lactoferrin was inoculated intranasally for 5 days, and then on the 12th day, the single inoculation of lactoferrin intranasally was performed as a challenge. On the 13th day, airway hypersensitivity was assessed (AHR), a bronchoalveolar fluid (BALF) cell analysis was conducted, serum IgE and serum lactoferrin‐specific IgG and IgE levels as well as the mRNA expression levels of cytokines and chemokines in the lung were measured, and a histopathological analysis of the lung was performed. Human lactoferrin increased AHR, the number of eosinophils in BALF, serum lactoferrin‐specific IgG levels, and the mRNA levels of IL‐13, eotaxin 1, and eotaxin 2. Moreover, the accumulation of inflammatory cells around the bronchus and the immunohistochemical localization of arginase I and human lactoferrin were detected. Collectively, these results indicate that human lactoferrin induced allergic airway inflammation in mice. Therefore, the commercial use of human lactoferrin in supplements warrants more intensive study.

PM2.5-induced airway inflammation and hyperresponsiveness in NC/Nga mice

The allergic inflammatory effects of particulate matter (PM) 2.5, collected with the cyclone system in Yokohama city in Japan, were investigated in NC/Nga mice, which are hypersensitive to mite allergens. PM2.5 with alum was injected intraperitoneally for sensitization. Five days later, 200 μg of PM2.5 in 25 μL of saline was administered to mice intranasally five times for further sensitization. On the 11th day, PM2.5 was administered as a challenge. On the 12th day, mice were examined for airway hyperresponsiveness (AHR), the bronchoalveolar lavage fluid (BALF) cell count, mRNA expression of Th₁ , Th₂ cytokines, and metallothioneins in lung tissue, and histopathology. PM2.5 increased AHR, total cell numbers including eosinophils in BALF, and mRNA levels of IL-5, IL-22, eotaxin, eotaxin 2, and metallothionein 3. In PM2.5-induced lungs, inflammation was observed around the bronchus. These results demonstrate that PM2.5 alone, collected with the cyclone system in Yokohama city in Japan, induces asthma-like airway inflammation. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1047-1054, 2017.

Oral administration of Lactobacillus paracasei L9 attenuates PM2.5-induced enhancement of airway hyperresponsiveness and allergic airway response in murine model of asthma

This study investigated allergy immunotherapy potential of Lactobacillus paracasei L9 to prevent or mitigate the particulate matter 2.5 (PM2.5) enhanced pre-existing asthma in mice. Firstly, we used a mouse model of asthma (a 21-day ovalbumin (OVA) sensitization and challenge model) followed by PM2.5 exposure twice on the same day of the last challenge. PM2.5 was collected from the urban area of Beijing and underwent analysis for metals and polycyclic aromatic hydrocarbon contents. The results showed that PM2.5 exposure enhanced airway hyper-responsiveness (AHR) and lead to a mixed Th2/ IL-17 response in asthmatic mice. Secondly, the PM2.5 exposed asthmatic mice were orally administered with L9 (4×107, 4×109 CFU/mouse, day) from the day of first sensitization to the endpoint, for 20 days, to investigate the potential mitigative effect of L9 on asthma. The results showed that L9 ameliorated PM2.5 exposure enhanced AHR with an approximate 50% decrease in total airway resistance response to methacholine (48 mg/ml). L9 also prevented the exacerbated eosinophil and neutrophil infiltration in bronchoalveolar lavage fluid (BALF), and decreased the serum level of total IgE and OVA-specific IgG1 by 0.44-fold and 0.3-fold, respectively. Additionally, cytokine production showed that L9 significantly decreased T-helper cell type 2 (Th2)-related cytokines (IL-4, -5, -13) and elevated levels of Th1 related IFN-γ in BALF. L9 also reduced the level of IL-17A and increased the level of TGF-β. Taken together, these results indicate that L9 may exert the anti-allergic benefit, possibly through rebalancing Th1/Th2 immune response and modulating IL-17 pro-inflammatory immune response. Thus, L9 is a promising candidate for preventing PM exposure enhanced pre-existing asthma.

Oral administration of Lactobacillus paracasei L9 attenuates PM2.5-induced enhancement of airway hyperresponsiveness and allergic airway response in murine model of asthma

This study investigated allergy immunotherapy potential of Lactobacillus paracasei L9 to prevent or mitigate the particulate matter 2.5 (PM2.5) enhanced pre-existing asthma in mice. Firstly, we used a mouse model of asthma (a 21-day ovalbumin (OVA) sensitization and challenge model) followed by PM2.5 exposure twice on the same day of the last challenge. PM2.5 was collected from the urban area of Beijing and underwent analysis for metals and polycyclic aromatic hydrocarbon contents. The results showed that PM2.5 exposure enhanced airway hyper-responsiveness (AHR) and lead to a mixed Th2/ IL-17 response in asthmatic mice. Secondly, the PM2.5 exposed asthmatic mice were orally administered with L9 (4×107, 4×109 CFU/mouse, day) from the day of first sensitization to the endpoint, for 20 days, to investigate the potential mitigative effect of L9 on asthma. The results showed that L9 ameliorated PM2.5 exposure enhanced AHR with an approximate 50% decrease in total airway resistance response to methacholine (48 mg/ml). L9 also prevented the exacerbated eosinophil and neutrophil infiltration in bronchoalveolar lavage fluid (BALF), and decreased the serum level of total IgE and OVA-specific IgG1 by 0.44-fold and 0.3-fold, respectively. Additionally, cytokine production showed that L9 significantly decreased T-helper cell type 2 (Th2)-related cytokines (IL-4, -5, -13) and elevated levels of Th1 related IFN-γ in BALF. L9 also reduced the level of IL-17A and increased the level of TGF-β. Taken together, these results indicate that L9 may exert the anti-allergic benefit, possibly through rebalancing Th1/Th2 immune response and modulating IL-17 pro-inflammatory immune response. Thus, L9 is a promising candidate for preventing PM exposure enhanced pre-existing asthma.

Effects of Asian Dust Particles on the Early-Stage Antigen-Induced Immune Response of Asthma in NC/Nga Mice

Asian dust (AD) can aggravate airway inflammation in asthma, but the association between AD and the development of asthma remains unclear. This study aimed to investigate the effects of AD on the early stage of antigen sensitization using a mouse model of asthma, as well as the role of leukotrienes (LTs) in antigen-induced airway inflammation potentiated by AD particles. NC/Nga mice were co-sensitized by intranasal instillation of AD particles and/or Dermatophagoides farinae (Df) for five consecutive days. Df-sensitized mice were stimulated with an intranasal Df challenge at seven days. Mice were treated with the type 1 cysteinyl LT (CysLT₁) receptor antagonist orally 4 h before and 1 h after the allergen challenge. At 24 h post-challenge, the differential leukocyte count, inflammatory cytokines, and LTs in bronchoalveolar lavage fluid were assessed, and airway inflammation was evaluated histopathologically. AD augmented neutrophilic and eosinophilic airway inflammation with increased CysLTs and dihydroxy-LT in a mouse model of asthma. The CysLT₁ receptor antagonist was shown to attenuate both neutrophilic and eosinophilic airway inflammation augmented by AD. Therefore, exposure to AD may be associated with the development of asthma and LTs may play important roles in airway inflammation augmented by AD.

The Effect of Seasonal Variations in Airborne Particulate Matter on Asthma-Related Airway Inflammation in Mice

This study aimed to investigate the effects of winter and spring particulate matter (PM) on airway inflammation and allergies in a mouse asthma model. PM was collected during 7–28 February 2013 (winter) and during 7–28 April 2013 (spring) in Yonago, Japan. NC/Nga mice were co-sensitized using intranasal instillation of the PMs and Dermatophagoides farinae (Df) for 5 consecutive days, and were subsequently challenged using intranasal Df at 7 days after the last sensitization. At 24 h after the challenge, serum immunoglobulin levels, differential leukocyte counts, and inflammatory cytokines levels were measured in the mice’s bronchoalveolar lavage fluid (BALF). Compared to co-sensitization using spring PM and Df, winter PM and Df induced greater increases in the BALF neutrophil and eosinophil counts and total serum IgE and IgG2a levels. Furthermore, winter PM-sensitized mice exhibited higher BALF levels of interleukin-5, interleukin-13, interleukin-6, and keratinocyte-derived chemokine. Therefore, we observed seasonal variations in the effects of PM on asthma-related airway inflammation. These findings suggest that the compositions of PM vary according to season, and that it is important to evaluate PM compositions in order to understand the associations between asthma and PM.

In Utero exposure to genistein enhanced intranasal house dust mite allergen-induced respiratory sensitization in young adult B6C3F1 mice

Despite many hypothesized benefits of dietary isoflavone genistein (GEN) deriving from soy-based products, questions surrounding GEN's developmental immunotoxic effects are increasing. To understand how in utero GEN exposure may modulate postnatal respiratory sensitization, we conducted a time course study using a common household allergen (house dust mites: HDM; 10μg/mouse) following intranasal instillation, a physiological route of allergen exposure. GEN was administered to dams by gavage from gestational day 14 to parturition at a physiologically relevant dose (20mg/kg bw). Female and male offspring were sensitized with HDM allergens beginning about one month prior to sacrifice followed by challenges with three weekly doses of HDM extracts, and they were euthanized at day 3 following the final HDM exposure at four different time points (postnatal day (PND) 80, 120, 160, and 200). In utero GEN combined with postnatal HDM exposures (GEN+HDM) increased total IgE production in both young female and male B6C3F1 offspring (e.g., PND 80 in females and PND 120 in males). Increased antigen-specific IgG1, IgG2a and IgG2b levels were also observed at various time points in both female and male offspring. In addition, increases in macrophage number in bronchoalveolar lavage fluid of both female and male GEN+HDM offspring at PND 80 and PND 120, respectively, were observed when compared to the vehicle group. For T cells, an increase over the vehicle in female GEN+HDM offspring was observed at PND 80. Due to similar patterns of increases, it seems likely that GEN+HDM-induced increases in total IgE and macrophages are related. Overall, in utero GEN plus later-life HDM exposures exert increases in total IgE and HDM-specific IgG production as well as macrophage recruitments to the lung in young adult mice.

Rebamipide suppresses mite-induced asthmatic responses in NC/Nga mice

Allergic asthma caused by continuous allergen exposure evokes allergen-specific Th2 responses and is characterized by chronic airway inflammation and hyperresponsiveness. A previous report showed that rebamipide improved asthmatic symptoms in an ovalbumin/trypsin mice model. However, it is still unclear how rebamipide exerts its effects in asthma. In this study, rebamipide improved the asthmatic responses induced by mite exposure in NC/Nga mice, revealing the mechanism of this therapeutic effect. Rebamipide suppressed the infiltration of eosinophils into the airways and lung as well as attenuating the production of reactive oxygen species in tissues. In addition to these anti-inflammatory effects, rebamipide inhibited the production of IL-33, a member of the IL-1 family that drives the subsequent production of Th2-associated cytokines. These observations identify the point where rebamipide exerts its suppressive action on asthma and suggest that rebamipide has therapeutic potential in preventing mite-induced asthma.

l-Arginine administration attenuates airway inflammation by altering l-arginine metabolism in an NC/Nga mouse model of asthma

Changes in l-arginine metabolism, including increased arginase levels and decreased nitric oxide production, are involved in the pathophysiology of asthma. In this study, using an intranasal mite-induced NC/Nga mouse model of asthma, we examined whether administration of l-arginine ameliorated airway hyperresponsiveness and inflammation by altering l-arginine metabolism. Experimental asthma was induced in NC/Nga mice via intranasal administration of mite crude extract (50 µg/day) on 5 consecutive days (days 0-4, sensitization) and on day 11 (challenge). Oral administration of l-arginine (250 mg/kg) was performed twice daily on days 5-10 for prevention or on days 11-13 for therapy. On day 14, we evaluated the inflammatory airway response (airway hyperresponsiveness, the number of cells in the bronchoalveolar lavage fluid, and the changes in pathological inflammation of the lung), arginase expression and activity, l-arginine bioavailability, and the concentration of NOx, the end products of nitric oxide. Treatment with l-arginine ameliorated the mite-induced inflammatory airway response. Furthermore, l-arginine administration attenuated the increases in arginase expression and activity and elevated the NOx levels by enhancing l-arginine bioavailability. These findings indicate that l-arginine administration may contribute to the improvement of asthmatic symptoms by altering l-arginine metabolism.

Influence of Asian dust particles on immune adjuvant effects and airway inflammation in asthma model mice

OBJECTIVE

An Asian dust storm (ADS) contains airborne particles that affect conditions such as asthma, but the mechanism of exacerbation is unclear. The objective of this study was to compare immune adjuvant effects and airway inflammation induced by airborne particles collected on ADS days and the original ADS soil (CJ-1 soil) in asthma model mice.

METHODS

Airborne particles were collected on ADS days in western Japan. NC/Nga mice were co-sensitized by intranasal instillation with ADS airborne particles and/or Dermatophagoides farinae (Df), and with CJ-1 soil and/or Df for 5 consecutive days. Df-sensitized mice were stimulated with Df challenge intranasally at 7 days after the last Df sensitization. At 24 hours after challenge, serum allergen specific antibody, differential leukocyte count and inflammatory cytokines in bronchoalveolar lavage fluid (BALF) were measured, and airway inflammation was examined histopathologically.

RESULTS

Co-sensitization with ADS airborne particles and Df increased the neutrophil and eosinophil counts in BALF. Augmentation of airway inflammation was also observed in peribronchiolar and perivascular lung areas. Df-specific serum IgE was significantly elevated by ADS airborne particles, but not by CJ-1 soil. Levels of interleukin (IL)-5, IL-13, IL-6, and macrophage inflammatory protein-2 were higher in BALF in mice treated with ADS airborne particles.

CONCLUSION

These results suggest that substances attached to ADS airborne particles that are not in the original ADS soil may play important roles in immune adjuvant effects and airway inflammation.

Inflammatory airway responses by nasal inoculation of suspended particulate matter in NC/Nga mice

To evaluate the allergic effect of airborne particulate matter (PM) on the airway, separated soluble supernatant (Sup) and insoluble precipitate (Pre) in suspended PM were inoculated into NC/Nga mice with a high sensitivity for mite allergens. Sup, Pre, or both Sup and Pre with or without pronase treatment were inoculated via the nasal route five times for sensitization and a challenge inoculation on the 11th day in NC/Nga mice. On the 14th day, mice were examined for airway hyperresponsiveness (AHR), bronchoalveolar lavage fluid (BALF) cell count, mRNA expression of Th1 and Th2 cytokines in the lung tissue, and histopathology. Synergistic effects of Sup and Pre were observed as increases in AHR and a histopathological change of Periodic acid-Schiff (PAS) staining. Increases in neutrophils, macrophages, and lymphocytes of BALF cells were dependent on Pre. The expression of IL-4 mRNA was increased by Sup, and those of IL-5 mRNA and Il-13 mRNA was increased by Sup and Pre. Augmented AHR, mRNA expression of IL-4, peribronchial inflammation, and PAS staining by Sup plus Pre were attenuated by treatment of Sup with pronase to digest proteins. These results suggest that some proteins of ambient PM may be important environmental factors for AHR and airway inflammation with the aid of insoluble particulates, although some soluble factors such as endotoxins cannot be ruled out.

Allergic airway inflammation by nasal inoculation of particulate matter (PM2.5) in NC/Nga mice

To evaluate the effect of airborne particulate matter 2.5 (PM_2.5) in winter on airway inflammation, water-soluble supernatant (Sup) and water-insoluble precipitate (Pre) in PM_2.5 were inoculated in NC/Nga mice with high sensitivity to mite allergens. Sup with aluminum oxide was injected intraperitoneally for sensitization. Five days later, Sup, Pre or both Sup and Pre were inoculated via the nasal route five times for more sensitization and a challenge inoculation on the 11th day in NC/Nga mice. On the 12th day, mice were examined for airway hyperresponsiveness (AHR), BALF cell count and IL-1β concentration, mRNA expression of Th₁ and Th₂ cytokines, chemokines such as eotaxin 1 and eotaxin 2, inflammasomal complex molecules such as IL-1β, caspase 1 and the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) in lung tissue as well as histopathology. The synergistic effect of Sup and Pre was observed in terms of increases in AHR, BALF cells, the mRNA expression of IL-13, eotaxin1 and IL-1β, and the IL-1β concentration in BALF. Intracellular deposits of insoluble particulates were observed in macrophages around inflammatory granulation of the mouse group treated with Sup and Pre. These results suggest that PM_2.5 can induce airway hyperresponsiveness in mice with genetically high sensitivity to mite allergens by an inflammasome-associated mechanism and synergistic action of insoluble particulates and soluble components.

Anti-inflammatory effect of arginase inhibitor and corticosteroid on airway allergic reactions in a Dermatophogoides farinae-induced NC/Nga mouse model

The present study was aimed to investigate the effect of an arginase inhibitor, N-hydroxy-nor-L-arginine (nor-NOHA) and a corticosteroid, prednisolone, in an intranasal mite-induced NC/Nga mouse model of asthma. The treatment with nor-NOHA and prednisolone inhibited the increase in airway hyperresponsiveness, the number of bronchoalveolar lavage fluid cells, protein expression of arginase I and arginase II, messenger RNA (mRNA) expression of nitric oxide synthase (NOS)2 and Th2 cytokines such as interleukin (IL)-4, IL-5, and IL-13, and the pathological inflammatory changes of the lung. NOx levels in the lung were not changed in mice treated with prednisolone and elevated in mice treated with nor-NOHA or prednisolone plus nor-NOHA despite suppressed NOS2 mRNA expression. The study concluded that anti-inflammatory effect by nor-NOHA might be dependent on NO supply from depleted NO by downregulated arginine availability of arginase and was not related with the anti-inflammatory mechanisms by prednisolone.

Corticosteroid administration reduces the concentration of hyaluronan in bronchoalveolar lavage in a murine model of eosinophilic airway inflammation

OBJECTIVE

To analyze the effect of corticosteroid administration on the concentration of hyaluronan (HA) in bronchoalveolar lavage (BAL) in a murine model of eosinophilic airway inflammation and to study the mechanisms involved.

MATERIALS AND METHODS

Untreated-mice or mice treated with 1 μg/g/day betamethasone (Bm) or 0.25 μg/g/day(-1) budesonide (Bd) were sensitized and challenged with Dermatophagoides pteronyssinus (Dp) or saline (control group). The concentration of HA in BAL was determined by ELISA. In vitro migration assays were performed using a Boyden chamber and the expression of HA synthases (HAS) was analyzed by RT-PCR.

RESULTS

We found a significant increase (P < 0.01) in the levels of HA in BAL from Dp-treated mice that was prevented by Bm or Bd. Corticosteroids also inhibited the increase in HAS expression, and the phosphorylation of Akt and ERK in the lungs of challenged mice. Finally, we found that low molecular weight HA induces the chemotaxis of BAL cells in vitro through a mechanism mediated by CD44.

CONCLUSION

We conclude that corticosteroids prevent the increase in HA in BAL from Dp-challenged mice. This effect is associated with reduced expression of HAS and reduced phosphorylation of Akt and ERK in the lungs of challenged mice.

Lack of transient receptor potential vanilloid-1 enhances Th2-biased immune response of the airways in mice receiving intranasal, but not intraperitoneal, sensitization

BACKGROUND

Transient receptor potential vanilloid-1 (TRPV1) may modulate allergic airway inflammation because it is expressed not only on the nerve endings but also on several cells of the immune system. We wanted to know the characteristics of airway and systemic responses against sensitization and challenge with allergens in TRPV1 receptor gene knockout mice (TRPV1(-/-)).

METHODS

TRPV1(-/-) and their wild-type counterparts (TRPV1(+/+)) were sensitized with either house dust mite (HDM) or ovalbumin (OVA) via intranasal (i.n.) or intraperitoneal (i.p.) route before the final i.n. challenge with the corresponding allergen. One day after the final challenge, serum IgE levels, cytokine levels in the bronchoalveolar lavage fluid (BALF), and the number of BALF cells were examined after measuring bronchial hyperresponsiveness against methacholine.

RESULTS

Compared to TRPV1(+/+), TRPV1(-/-) showed enhanced Th2-biased response after i.n. HDM or OVA sensitization, including increased levels of serum IgE, interleukin 4 (IL-4) and eosinophils in the BALF. By contrast, when sensitized via i.p. route, the response against OVA or HDM was almost similar between TRPV1(+/+) and TRPV1(-/-).

CONCLUSION

TRPV1 receptor may downregulate Th2-biased immune response when sensitized via airways, although this was not the case when sensitized systemically.

Strain-dependent genomic factors affect allergen-induced airway hyperresponsiveness in mice

Asthma is etiologically and clinically heterogeneous, making the genomic basis of asthma difficult to identify. We exploited the strain-dependence of a murine model of allergic airway disease to identify different genomic responses in the lung. BALB/cJ and C57BL/6J mice were sensitized with the immunodominant allergen from the Dermatophagoides pteronyssinus species of house dust mite (Der p 1), without exogenous adjuvant, and the mice then underwent a single challenge with Der p 1. Allergic inflammation, serum antibody titers, mucous metaplasia, and airway hyperresponsiveness were evaluated 72 hours after airway challenge. Whole-lung gene expression analyses were conducted to identify genomic responses to allergen challenge. Der p 1-challenged BALB/cJ mice produced all the key features of allergic airway disease. In comparison, C57BL/6J mice produced exaggerated Th2-biased responses and inflammation, but exhibited an unexpected decrease in airway hyperresponsiveness compared with control mice. Lung gene expression analysis revealed genes that were shared by both strains and a set of down-regulated genes unique to C57BL/6J mice, including several G-protein-coupled receptors involved in airway smooth muscle contraction, most notably the M2 muscarinic receptor, which we show is expressed in airway smooth muscle and was decreased at the protein level after challenge with Der p 1. Murine strain-dependent genomic responses in the lung offer insights into the different biological pathways that develop after allergen challenge. This study of two different murine strains demonstrates that inflammation and airway hyperresponsiveness can be decoupled, and suggests that the down-modulation of expression of G-protein-coupled receptors involved in regulating airway smooth muscle contraction may contribute to this dissociation.

Direct inhibition of arginase attenuated airway allergic reactions and inflammation in a Dermatophagoides farinae-induced NC/Nga mouse model

The expression of arginase I has been a focus of research into the pathogenesis of experimental asthma, because arginase deprives nitric oxide synthase (NOS) of arginine and therefore participates in the attenuation of bronchodilators such as nitric oxide (NO). The present study used an intranasal mite-induced NC/Nga mouse model of asthma to investigate the contribution of arginase to the asthma pathogenesis, using an arginase inhibitor, N(omega)-hydroxy-nor-l-arginine (nor-NOHA). The treatment with nor-NOHA inhibited the increase in airway hyperresponsiveness (AHR) and the number of eosinophils in bronchoalveolar lavage fluid. NOx levels in the lung were elevated despite suppressed NOS2 mRNA expression. Accompanied by the attenuated activity of arginase, the expression of arginase I at both the mRNA and protein level was downregulated. The levels of mRNA for T helper 2 cytokines such as IL-4, IL-5, and IL-13, and for chemotactants such as eotaxin-1 and eotaxin-2, were reduced. Moreover, the accumulation of inflammatory cells and the ratio of goblet cells in the bronchiole were decreased. The study concluded that the depletion of NO caused by arginase contributes to AHR and inflammation, and direct administration of an arginase inhibitor to the airway may be beneficial and could be of use in treating asthma due to its anti-inflammatory and airway-relaxing effects, although it is not clear whether the anti-inflammatory effect is direct or indirect.

Preparation and Characterization of a Polyclonal Antibody against Brominated Protein

(Di)bromotyrosine is formed by the specific reaction of eosinophil peroxidase and can be used as an eosinophil activation marker. In the present study, an antibody for (di)bromotyrosine in proteins was prepared to investigate the pathogenesis of eosinophil-related diseases such as allergic responses. A rabbit polyclonal antibody was raised against brominated keyhole limpet hemocyanin. The specificity of the antiserum was investigated with an enzyme-linked immunosorbent assay (ELISA). The antiserum recognized brominated bovine serum albumin (BSA) and dibromotyrosine-conjugated BSA. The antiserum also reacted with chlorinated BSA and di-iodotyrosine-conjugated BSA. Moreover, the specificity of the antiserum was investigated using competitive ELISA. Dibromotyrosine and di-iodotyrosine inhibited the recognition of brominated BSA by the antiserum. However, the recognition of brominated BSA by the antiserum was not inhibited by bromotyrosine, chlorotyrosine, iodotyrosine, nitrotyrosine, aminotyrosine, phosphotyrosine, or tyrosine. These results suggested that the epitope of the antiserum is dihalogenated tyrosine. Immunohistochemically, the antiserum stained brominated rat eosinophils but not chlorinated or nitrated eosinophils. In conclusion, an antiserum for dihalogenated protein was prepared. It is expected that the antiserum will be useful for the analysis of the pathogenesis of allergic diseases such as asthma and atopic dermatitis.

Transiently, paralleled upregulation of arginase and nitric oxide synthase and the effect of both enzymes on the pathology of asthma

Changes in the expression of arginase and their association with nitrosative stress were investigated using an asthmatic model previously established in NC/Nga mice with mite extract. Mite crude extract (100 microg/day) from Dermatophagoides farinae was administered intranasally for 5 consecutive days (day 0-4), and a single challenge was performed on day 11. On day 12, upregulation of the mRNA expression of inducible types of nitric oxide synthase (iNOS) and increases in immunohistochemical staining for iNOS and nitrotyrosine were observed. However, the level of nitrite + nitrate was unchanged. An increase in enzymatic activity, upregulation of mRNA expression, and immunostaining for arginase I was detected in the lung tissue and serum. Moreover, increases in both arginase I and II were revealed by immunoblotting. Goblet cell hyperplasia in bronchial epithelial cells and increasing collagen synthesis around the bronchus were also observed. These results suggested that an increase in arginase may lead to decreased availability of arginine for nitric oxide synthase and may contribute to the remodeling of the lung.

Potentiation of pulmonary reflex response to capsaicin 24h following whole-body acrolein exposure is mediated by TRPV1

Pulmonary C-fibers are stimulated by irritant air pollutants producing apnea, bronchospasm, and decrease in HR. Chemoreflex responses resulting from C-fiber activation are sometimes mediated by TRPV1 and release of substance P. While acrolein has been shown to stimulate C-fibers, the persistence of acrolein effects and the role of C-fibers in these responses are unknown. These experiments were designed to determine the effects of whole-body acrolein exposure and pulmonary chemoreflex response post-acrolein. Rats were exposed to either air or 3 ppm acrolein for 3 h while ventilatory function and HR were measured; 1-day later response to capsaicin challenge was measured in anesthetized rats. Rats experienced apnea and decrease in HR upon exposure to acrolein, which was not affected by either TRPV1 antagonist or NK(1)R antagonist pretreatment. Twenty-four hours later, capsaicin caused apnea and bronchoconstriction in control rats, which was potentiated in rats exposed to acrolein. Pretreatment with TRPV1 antagonist or NK(1)R antagonist prevented potentiation of apneic response and bronchoconstriction 24h post-exposure. These data suggest that although potentiation of pulmonary chemoreflex response 24h post-acrolein is mediated by TRPV1 and release of substance P, cardiopulmonary inhibition during whole-body acrolein exposure is mediated through other mechanisms.

Galectin-9 inhibits CD44-hyaluronan interaction and suppresses a murine model of allergic asthma

RATIONALE

Galectin-9 (Gal-9) belongs to the galectin family, which exhibits affinity for beta-galactosides. Gal-9 has a variety of biological activities; however, its role in allergic inflammation is unknown.

OBJECTIVES

We evaluated the effect of a stable form of the human protein on allergic airway inflammation in a mite allergen-induced asthma model.

METHODS

Human stable Gal-9 was given by intravenous injection to mice during antigen challenge. The effect of Gal-9 on airway inflammation and airway hyperresponsiveness (AHR) was then evaluated.

MEASUREMENTS AND MAIN RESULTS

Gal-9 reduced AHR as well as Th2-associated airway inflammation. Furthermore, administration of Gal-9 as well as anti-CD44 monoclonal antibody inhibited the infiltration of peripheral blood Th2 cells into the airway. Interestingly, Gal-9 directly bound the CD44 adhesion molecule and inhibited interactions with hyaluronan (HA). Consistent with the concept that CD44-HA interactions mediate the migration of T cells into the lung, Gal-9 blocked CD44-dependent adhesion of BW5147 mouse T cells to HA.

CONCLUSIONS

We conclude that Gal-9 inhibits allergic inflammation of the airway and AHR by modulating CD44-dependent leukocyte recognition of the extracellular matrix.

Intranasal coadministration of live lactococci producing interleukin-12 and a major cow's milk allergen inhibits allergic reaction in mice

The Th1/Th2 balance deregulation toward a Th2 immune response plays a central role in allergy. We previously demonstrated that administration of recombinant Lactococcus lactis strains expressing bovine beta-lactoglobulin (BLG), a major cow's milk allergen, partially prevents mice from sensitization. In the present study, we aimed to improve this preventive effect by coadministration of L. lactis BLG and a second recombinant L. lactis strain producing biologically active interleukin-12 (IL-12). This L. lactis strain producing IL-12 was previously used to enhance the Th1 immune response in a tumoral murine model (L. G. Bermúdez-Humarán et al., J. Immunol. 175:7297-7302, 2005). A comparison of the administration of either BLG alone or BLG in the presence of IL-12 was conducted. A BLG-specific primary Th1 immune response was observed only after intranasal coadministration of both L. lactis BLG and IL-12-producing L. lactis, as demonstrated by the induction of serum-specific immunoglobulin G2a (IgG2a) concomitant with gamma interferon secretion by splenocytes, confirming the adjuvanticity of IL-12-producing L. lactis. Immunized mice were further sensitized by intraperitoneal administration of purified BLG, and the allergic reaction was elicited by intranasal challenge with purified BLG. Mice pretreated with BLG in either the presence or the absence of IL-12 were rendered completely tolerant to further allergic sensitization and elicitation. Pretreatment with either L. lactis BLG or L. lactis BLG and IL-12-producing L. lactis induces specific anti-BLG IgG2a production in serum and bronchoalveolar lavage (BAL) fluid. Although specific serum IgE was not affected by these pretreatments, the levels of eosinophilia and IL-5 secretion in BAL fluid were significantly reduced after BLG challenge in the groups pretreated with L. lactis BLG and L. lactis BLG-IL-12-producing L. lactis, demonstrating a decreased allergic reaction. Our data demonstrate for the first time (i) the induction of a protective Th1 response by the association of L. lactis BLG and IL-12-producing L. lactis which inhibits the elicitation of the allergic reaction to BLG in mice and (ii) the efficiency of intranasal administration of BLG for the induction of tolerance.